1. Field of the Invention
The present invention relates to a reduction device having a reverse rotation preventing function, and more particularly, the present invention relates to a reduction device having a reverse rotation preventing function, which uses a planetary gear for reducing a rotational velocity of an output shaft when transferring a rotational velocity of an input shaft to the output shaft in various machine tools or industrial machines, whereby high reduction ratio is obtained while effectively restraining the input shaft from being reversely rotated by preventing driving force of the output shaft from being transferred back to the input shaft.
2. Description of the Prior Art
Generally, various machine tools or industrial machines are equipped with a reduction device which serves to change a driving RPM generated by and transferred from a power source to other RPMs suitable for operating them.
For example, in a conveyor such as a belt conveyor, chain conveyor or the like, since it is required to apply force for moving a belt or chain while reducing a driving RPM for causing the belt or chain to be moved at a predetermined velocity, driving means having a reduction device, such as a geared motor, is provided. Further, in a lifting facility for lifting a weight, such as a hoist, since it is required to keep a height of a lifted weight constant, a separate reverse rotation preventing device is provided for braking a reverse load transferred to an input shaft from an output shaft when a power source is shut off.
On the other hand, a typical reduction device uses a combination of a plurality of spur gears each of which has a different number of teeth, or adopts a reduction scheme which employs warm gears.
However, as described above, a reduction device applied to a lifting facility has a problem in that a separate reverse rotation preventing device must be additionally provided for preventing a load of an output shaft from being transferred to an input shaft. Also, a reduction device which uses a combination of a plurality of spur gears or warm gears, suffer from defects in that since a kinematic mechanism thereof is relatively involved, the number of components increases whereby volume and manufacturing cost are elevated, and since the whole load acts on only a single tooth, one at a time when gears are meshed one with another, each tooth is apt to be abraded whereby endurability and operation reliability are deteriorated.